INTRODUCTION: Bedside thoracic ultrasound has been shown to be a valuable diagnostic tool in the emergency department. The purpose of this study was to evaluate the feasibility of bedside thoracic ultrasound in the prehospital HEMS setting.SETTING: Air ambulance helicopters during patient transportation.METHODS: This was a prospective pilot study. 71 consecutive, nonpregnant patients over 18 years old were enrolled. While in flight, providers completed limited bedside thoracic ultrasounds with the patient supine and recorded their interpretation of the presence or absence of the ultrasonographic sliding lung sign on a closed data-set instrument.RESULTS: 41 (58%) of the eligible patients had a recorded thoracic ultrasound acquired in flight. The level of agreement in image interpretation between the flight crew and expert reviewer was substantial (Kappa 0.67, CI 0.44-0.90). The reviewer rated 54% of all images as "good" in quality. The most common reason cited for not completing the ultrasound was lack of enough provider time or space limitations within the aircraft cabin.CONCLUSION: The results of this study suggest that, with limited training, bedside thoracic ultrasound image acquisition and interpretation for the sliding lung sign in the HEMS setting is feasible.